Method and apparatus for producing ball-like nodules of fine-grained ores and minerals



Nqv. 28, 1961 o ROLFS'EN 3,010,145

METHOD AND APPARATUS FOR PRODUCING BALL-LIKE NODULES OF FINE-GRAINED ORES AND MINERALS 2 Sheets-Sheet 1 ET P1- T 'i 2- Filed March 1, 1957 ATTXi',

Nov. 28, 1961 o ROLFSEN 3,010,145

METHOD AND APPARATUS OR PRODUCING BALL-LIKE NODULES OF FINE-GRAINED ORES AND MINERALS Filed March 1, 1957 2 Sheets-Sheet 2 United States Patent Ofiice 3,010,145 Patented Nov. 28,- 1 961 Ole Rolfsen, Gyldenlovesgate 19, Oslo,

Filed Mar. Claims priorizty,

Norway 1, 1957, Ser. No. 643,434 application Norway Mar. 8, 1956 Claims. (Cl. 18-1) The present invention relates to apparatus for producing ball-shaped nodules formed by the agglomeration of finely divided solids.

Agglomeration of fine-grained solids such as ores and minerals is effected by supplying thereto a moistening liquid and mixing the same intimately into the material either in mixing screws, drums or inclined cups. In the mixing screws a more lumpy material is obtained, whereas in drums and cups approximately ball-shaped nodules are formed due to rotation. The size of the balls may be varied according to the requirements imposed by the subsequent treatment, such as burning, roasting or reduction 1n various processes.

It is important to obtain balls having the greatest possible mechanical strength so that they will retain their shape during the further treatment.

The ball formation is effected by rolling fresh material onto a moistened surface. However, if these balls are heated in subsequent processes, the liquid will evaporate and the balls will easily fall apart. It is therefore natural to use binding agents, but in order that these may increase the strength it may be necessary to add them in such amounts that the chemical composition of the material is substantially altered. This is the case for example when lime is used. If starches, glues or the like are used, the effect of these agents will disappear together with the moistening liquid, and the porosity of the balls may even be increased by the evaporation of the binder. This drawback becomes particularly marked in the case of balls of relatively small size, such as is desired for socalled micropellets to be burned on draft sintering grates.

However, it has been found that it is possible to increase the strength of the balls both in green condition, that is as unburned balls, and during the subsequent processes by giving the rolled balls a coating of binders of the type comprising hydrate of lime, water glass, borax, bentonite and the like, either individually or in certain combinations. Whereas by mixing the binder into the material during the rolling of the balls it is mostly necessary to use quantities amounting to 1 to 2 percent, it is possible by applying a subsequent coating to reduce the amount to for example A to /2 percent.

The present invention has for an object to agglomerate fine-grained material into ball-like nodules of a desired strength in a continuous process based on these known facts and primarily consists in compressing the material while it is in a moist condition into a packed consistency, thencrumb ling the same and thereafter rolling it into ball-like nodules. Thus, a compacting of the mass is obtained at the first stage, whereby the subsequent rolling into balls is facilitated. Contrary to known processes in which the rolling takes place either in a snowballlike manner from a small particle size, which requires a high water content which, in turn, makes it diflicult to obtain a high strength, or on recycled cores which reduces the output, in the present case the rolling is started with crumbs of a pre-compacted material, and the ball formation may then take place with a relatively small moisture content, and during rolling, after a more or less ball-like shape has been obtained, the balls may be provided with a coating which contributes in making them resist drying and heating without falling apart.

When using the invention it may be convenient to decrease the surface tension by means of surface-active additions (so-called detergents) such as Teepol, and at the same time make the liquid basic by adding, for example, haydrate of lime or the like. Thereby it is possible to obtain thinner films of liquid, whereby the amount is reduced and the adhesion will be increased so as to reduce disintegration during drying.

It was also found that an addition of heated heavy oils will facilitate a formation of balls in combination with the lowering of the surface tension mentioned above. This oil addition may also be kept in the order of about /2 to 1 percent without any harmful effect.

For carrying out the process the use of various forms of continuously operating apparatus is contemplated. However, it is preferred to use an apparatus which has been designed particularly with a view to the present process and which also forms part of the present invention. This apparatus, which will be described in detail in the following specification, may be adapted for producing balls ranging from very small to very large sizes, that is with diameters from 1 millimeter up to 50 to 60 millimeters. While it is possible to use the apparatus without moistening liquids, the efiiciency will be increased v by the use of such liquids.

The object of the apparatus is primarily to form balls with the least possible moisture and having the greatest possible strength. With this object in view the following procedure is adopted:

The form of apparatus used constitutes a development of the inclined cylinder bottom, the so-called Granulierteller, either all or part of the material being supplied thereto with an addition of moistening liquid and further addition or additions, if any, being effected in finely divided form. In the outer zone the material is pressed into packed condition by the action of centrifugal force or by rolls or by both in combination. Thereafter, it

is crumbled, preferably by means of channel-shaped scrapers which scrape the material off, and is thenpassed into an internal zone in which the centrifugal force is reduced, whereby a rolling on the bottom of the cup is made possible. During rolling the material scraped off will succesively adopt a globular shape, and the balls may be increased to a desired size by further supply of finely divided material and moistening liquid. By means of scrapers and vanes the material is then passed into one or more zones located further inwardly, in which fresh layers of binders and/or drying agents-for example unmoistened fine solids of the same material as.

the balls-may be applied. The finished material can then be removed through a chute or a central funnel and As it has been found that the ball size depends on the rotational speed and the slope of the bottom, it will be of great importance to be able to control the velocity of the various zones. A first step is therefore to divide the bottom of the cup into two or more separate cups capable of being rotated with mutually different angular velocities and, if desired, also with opposite directions of rotation. Preferably the individual cups are equipped with adjustable driving means and mounted on a common. frame, which is pivoted for adjustment of the inclination of the axis, usualy between 30 and 60 degrees.

With a view-to obtaining a desired course of the ballrolling dependent on the material to be treated, scraping and guiding members, which preferably are adjustable, may be provided in convenient places in the ball-rolling zone or zones for scraping material from the cups, or for guiding the balls during rolling and during transfer from one zone to the next.

The bottoms of the various cups may be of different shape and be placed at different levels. The bottom may be plane or conical, and the bottoms of the cups may be placed in one plane or one above or one below the others in staggered relation.

Further features of the invention will appear from the following specification, reference being; had to the accompanying drawings.

FIGS. 1 and 2 are diagrammatic sectional views illustrating different examples of possible arrangements of the various treating zones relative to each other.

FIG. 3 is a side view, partly in section, of an embodiment of an apparatus according to the invention.

FIG. 4 is a sectional view along the line lV-'IV in FIG. 3.

FIG. 5 shows the apparatus of FIG. 3 as viewed in axial direction from the top and with parts broken away for clearness of illustration.

FIGS. 6 and 7 are detail views on a larger scale along the lines VIVI and VI I-Vil respectively in FIG. 5.

FIG. 1 illustrates how a series of treating zones in accordance with the invention can be formed by annular cups 1, 2 and 3, arranged stepwise one below the other with successively decreasing diameters and with central discharge 4.

Each annular cup is angular in cross section so as to form a bottom and a peripheral flange, and the bottom of one cup projects inside the periphery of the next one, so that during rotation of the cup material may be discharged from one cup to the other, preferably in the proximity of the uppermost position by the action of gravity and/ or by means of suitable guiding members. In FIG. 2 a series of annular cups 5', 6 7 are shown to be arranged stepwise above each other, counting radially inwards, and likewise with a central discharge 8'. Also in this case the cups overlap each other radially and the material is assumed to'be delivered in a direction radially inwards from one cup to the next, which in this case, of course, requires guiding members for the transfer. The cups are presumed to rotate with suitable velocities, adapted for the treating processes desired in the various zones, such as compression, supply of material for ball format-ion, supply of binder and supply of' fuel. In any case it may be desiredtto extend the system further by adding further cups as indicated in dash-and-dot lines at 9' and 10 respectively. Further, it is contemplated that, instead of removing the material through a central orifice in the innermostcup, to remove it through an inclined chute on top of the cups as indicated in dash-and-dot lines at 1 1 and 12 respectively in FIGS. 1- and 2.

FIGS. 3 to 7 constitute a more complete showing of an embodiment of an apparatus constructed according to the principle illustrated in FIG. 1.

On a shaft 15, supported by a base 13 rigidly mounted on a fioor 14, a supporting structure 16 is pivoted, which is arranged as a two-armed lever and the inclination of which can be fixed and adjusted by means of an adjusting screw 17, which is provided with a hand-wheel 18 and pivoted on the base at 19, and which is engaged by a nut 2t} pivoted on the pivoted frame 16. To the frame 16 there are fixed a supporting cup 21 and, concentrically inside the same, a downwardly curved discharge pipe 22, opening into the interior of a fixed discharge pipe 23. In the interior of the cup 21 three supporting rings 24, 2 5 and 26 of angular cross section are mounted rotatably by means of axially and radially acting rollers 27 and 28, 29 and 30, and 31 and 32, respectively, distributed circumferentially within the cup in rows, each comprising three rollers and arranged stepwise one above the other. Rigidly attached to the rings 24, 25 and 26 by suitable connecting means are annular cups 33, 34 and 35 respectively, which extend stepwise one above and outside the other and above the supporting cup 21. Finally, by means of rigid external arms 36 the cup 21 carries a spider or similar supporting structure 37, which extends on top of the cups 33, 34 and 35 and carries various means which will be described later, for supply and treatment of the material.

For rotating the mounting rings 24, 25 and 26 with the cups 33, 34 and 35 respectively in the example shown driving belts 38, 39 and 40 are used, which extend in some cases above, and in some cases through openings in the supporting cup 21 and connect the mounting rings to suitable driving means mounted on the frame 16 which driving means counter-balance the cup 21 and the elements carried by the latter. For example, FIG. 4 shows two driving motors 41 and 42, which through suitable gearings drive the rings 24 and 26 and the ring 25, respectively. This causes the cups 33 and 35 to rotate in the same direction and the cup 34 in the opposite direction. If desired, the rotational speeds of the individual cups are separately adjustable by means of variators, oil gears, electric control means or the like, so that the speed of the cups and hence the effect of centrifugal force may be adapted according to the course of the treatment desired in the individual zones, while the effect of gravity on the movement of the material may at the same time be controlled by adjusting the inclination of the cups by means of the hand-wheel 18.

The spider or supporting structure 37 on top of the apparatus carries various treating means, which as illustrated in FIG. 5 may comprise movably supported weight- -loaded radially and axially acting pressure rolls 43 and 44, respectively, in the outermost zone, a transfer channel 45 between the outermost and the intermediate zone, movable guiding members 46, 46 and 47, 47 in the intermediate and the innermost zone, respectively, and fixed and/or movable scrapers 48 and 49 respectively. Likewise the spider may, if desired, carry a discharge chute 11 (indicated in dash-and-dot lines in FIGURE 5) as mentioned above in. connection with FIG. 1, if it is desired to remove the material on top of the apparatus instead of providing the innermost cup 33 with a. central orifice 50 for discharging material through pipe 22, as

shown."

One or more of the cups of the apparatus may con-- veniently be provided with. U- or V-shaped. grooves as shown specifically at 51 for the bottom and peripheral wall of the outermost cup 35in FIGS. 6 and 7, in which the grooves extend in a circumferential direction and contribute to theformation of the material into balls,

and likewise. also the rolls 43 and 44 may be provided.

with circumferential grooves as shown in FIG.

35 of the In the example shown the-outermost cup apparatus is assumed. to rotate counter-clockwise as viewed in FIG. 5, and material is supplied through a feed pipe. 52 over the lower portion of the cup. The material may be supplied either in a finely divided dry condition or wholly or partly moistened by finely divided moistening liquid. As mentioned above, it is preferable to use a basic moistening liquid comprising a surface-active substance with the addition of a base and, if desi'red,.also

hot oil, such as heavy oil.' If the material is dry or insufificiently moistened, moistening liquid is supplied through a pipe 53 with a spraying nozzle over the cup 35 immediately after the supply of material thereto. In such moistened condition the material is suited, in a-preliminary step preceding the rolling into balls, to be compressed into a more dense consistency, which takes place in the outer zone formed by the cup 35, partly due to the centrifugal force which urges the material outwardly, and partly due to the action of the rolls 43 and 44, which press the material against the circumferential wall and the bottom of the cup, respectively, whereby a layer of material of a desired substantially even thickness is immediately obtained.

- When the material reaches the channel 45, it is scraped from the cup 35, the channel being conveniently formed with teeth 54 at the front edge corresponding to the grooves 51 of the cup. As shown in FIGS. and 7 the channel 45 has such a shape that consequent to the pushing on the material from behind it conveys the latter inwardly into the cup 34, which is located inwardly of the first cup and in which the material arrives in crumbled form as gritor flake-formed crumbs due to the scraping action of the channel referred to above. However, as shown in FIGS. 6 and 7, the channel 45 is formed with a grate 55 in its bottom, whereby material under a certain size will fall therethrough and continue on in the outer cup 35 so as to be subjected to renewed compression together with fresh material. For adapting the slope of the channel and hence the effect of pushing from behind, the channel 45 is conveniently mounted for circumferential adjustment on a correspondingly curved supporting arm 56 or the like.

The channel 45 preferably conveys the material in a downward direction onto the upwardly moving side of the cup 34, which in the present case is assumed to rotate clockwise. The lumps or crumbs of material which at the beginning are of irregular shape, will thereby have a rolling motion imparted to them, which, besides, may partly be started already in the downwardly sloping portion of the channel, and will successively adopt a more and more globular shape. At the same time, due to the effect of centrifugal force caused by the rotation of the cup 3d, they are passed outwardly towards the circumferential wall of the latter and are entrained to the upper portion of the cup, where a greater or smaller part thereof be come entrapped between the guiding members 46 subject to the adjustment of the latter. It has been found in this connection that the larger balls will have the greatest tendency to roll down between the guiding members by the action of gravity, whereas the finer solids continue in the circumferential motion and thus are permitted to perform continued rolling. Clinging of the material to the cup 34 is prevented by the scrapers 48 and 49, some or all of which may, if desired, also be adjustable in order as far as possible to keep the cup clean and/or at the same time to perform a desired guiding action on the material.

It will be understood that the time of the ball-rolling and. hence also the ball-rolling effect on the cup 34 will depend both on the inclination of the cup and on the rotational speed of the latter, so that by the control of these factors in connection with the adjustment of the guiding vanes 46 very extensive possibilities of control are obtained. If an increase of the ball size is desired in the ball-rolling zone, it is possible in addition to supply further material through a feed pipe 57, either in a suitably moist condition or with simultaneous supply of moistening liquid througr a separate pipe 53. The tendency tosticking which this may involve, especially if also a thick oil is added, can be overcome by means of the scrapers referred to above. Generally, however, the centrifugal force does not cause a packing of material to an undesirable extent at the periphery of the cup, and for this reason, with the relative dimensions shown, it is preferable as a rule to keep the rotational speed of the cup 34 lower than that of the cup 35. Thus, good results have been obtained with a centrifugal force equal to 1.2 times the weight in the packing zone, but only a centrifugal force of about 0.7 times the weight in the ball-rolling zone.

The ball-shaped particles of desired size, which roll down between the guiding vanes 46, will fall from the cup 34 onto the cup 33, on which the ball-rolling is con tinued, a further layer being supplied through a feed conduit 59. This may be a binder, a drying agent or fuel, if desired, in combination with additional moistening liquid. Also in this zone the rotational speed is selected dependent on the desired rolling effect or particle size, so that coated balls of a suitable size are obtained which will roll down between the guiding vanes 47, Whereas finer or uncoated material will continue in rotation for further ball-rolling. Of course, also in this zone fixed or movable scrapers may be provided, if desired, and these as well as the scrapers 48 and 49 mentioned above may also be formed with teeth.

From the preceding description it will be apparent that by using the invention it is possible by physical and chemical means to improve the production of balls for a subsequent heat treatment, and likewise that the production of the balls can be effected continuously and with possibilities of control within wide limits with one single apparatus.

Many modifications may be contemplated within the scope of the invention. Apart from the use of more than three zones and different arrangements of the same as indicated in FIGS. 1 and 2, it may for example also be contemplated, instead of mounting the individual annular bottoms or cups concentrically about a common axis of rotation, to form one or more of the zones with an excentric circumferential wall, so as to obtain a more or less pronounced throwing action on the material. Likewise, it may be contemplated to form the circumferential wall of one zone as a flange projecting downwards from the bottom located over it, instead of as a flange projecting upwards from the appurtenant bottom, and in the case of an excentric rotation of the circumferential wall with respect to the axis of rotation of the lower bottom it will hereby also be possible to achieve a more or less pronounced scraping action at the periphery. Further, it may be contemplated to make one or more cups with a conical step-shaped or curved bottom instead of.

a plane bottom. The fixed or adjustable scrapers and vanes shown, which serve to keep the cup bottoms clean or to guide the material respectively, may according to prevailing conditions be placed otherwise than shown, for example it is possible to place scrapers or vanes in the upper or the upwardly moving portion of the ball-rolling zone in order to guide the material into areas with less centrifugal effect and hence greater possibilities of free ball-rolling or of rolling towards the outlet. Likewise, especially in larger structures, the scrapers may, if desired, be replaced wholly or in part by worms or other moving members. The forms illustrated of central discharge through furmel or chute may also be replaced by other discharge structures, for example involving an overflow to a stationary channel from the periphery of the innermost cup at the lowermost portion thereof.

I claim:

-1. Apparatus for the continuous production of balllike nodules of minerals, fine-grained ore and the like comprising: a support rotatably mounted in said apparatus, said support being adapted to receive the material used for the production of said ball-like nodules and having a central opening formed therein; said support, when rotating, being adapted to compress said material; means operatively connected to said support for driving the same; means for feeding said material to said support, at least one nodulising cup rotatably mounted in said apparatus underneath and substantially parallel to said support and being adapted to roll said compressed material into ball-like nodules; means operatively connected to said nodulising cup for rotating the same; means adapted to crumble the material compressed on said support and to transport the crumbled material to said nodulising cup through said central opening, and discharge means adapted to discharge said ball like nodules from said nodulising cup.

2. Apparatus for the continuous production of balllike nodules of minerals, fine-grained or and the like comprising: a high-velocity compressing cup having a rim portion rotatably mounted in an inclined position in said apparatus and adapted to receive the material used for the production of ball-like nodules, said cup having a central opening formed therein; said cup when rotating at a high-velocity centrifugally compressing said ma terial against said rim portion; means operatively connected to said high-velocity compressing cup for rotating the same; means for feeding said material to said high-velocity compressing cup, at least one nodulising cup rotatably mounted in said apparatus underneath and inclined in the same direction as said compressing cup, said nodulizing cup being positioned to receive material discharged from said central opening in said compressing cup and being adapted to roll said compressed material into ball-like nodules; means operatively connected to said nodulising cup for rotating the same; means adapted to crumble the material compressed on said high-velocity compressing cup and discharge the crumbled material through said central opening for delivery to said noduliz ing cup, and discharge means adapted to discharge said ball-like nodules from said nodulising cup.

3. Apparatus for the continuous production of balllike nodules of minerals, fine-grained ore and the like as claimed in claim 1 including at least one roller operatively connected to said support adapted to compress said material received by said support.

4. Apparatus for the continuous production of balllike nodules of minerals, fine-grained ore and the like comprising: a support movably mounted in said apparatus adapted to receive the material used for the production of ball-like nodules; said support when moving adapted to compress said material; means operatively connected to said support for driving the same; means for feeding said material to said support, a first nodulising cup rotatably mounted in said apparatus inwardly of said support and adapted to roll said compressed material into ball-like nodules; means operatively connected to said first nodulising cup for rotating the same; means adapted to crumble said compressed material and to transport said crumbled material from said moving support to said nodulising cup; a second nodulising cup rotatably mounted in said apparatus inwardly from said first nodulising cup adapted to further shape said crumbled material into ball-like nodules; means operatively connected to said second nodulising cup for rotating the same; means adapted to feed ball-like nodules from said first to said second nodulising cup, and discharge means adapted to discharge said ball-like nodules from said second nodulising cup.

5. Apparatus according to claim 1, including adjusting means operatively connected to said support for adjust-- ing the inclination thereof with respect to the horizontal axis of said apparatus.

6. Apparatus according to claim 4-, in which means is provided, in the rotative path of said first nodulising cup, eccentric to the axis of rotation of said first nodulising cup, for periodically deflecting the material carried by said first nodulising'cup.

7. Apparatus according to claim 6, in which said means comprises an adjustable wall positioned over said first nodulising cup.

8. Apparatus according to claim 2, wherein said high velocity compressing cup rotates in a direction opposite to the rotating direction ofsaid nodulising cup.

9. Apparatus as claimed in claim 4, wherein said first nodulising cup rotates in a direction opposite to said second nodulising cup.

10. Apparatus as claimed in claim 4, wherein said rotating means for said first nodulising cup and said sec-' ond nodulising cup rotate, respectively, said first nodulising cup and said second nodulising cup at different angular velocities.

11. Apparatus according to claim 1, wherein said support defines a plurality of grooves.

12. Apparatus according to claim 1, wherein said means adapted to crumble the material and transport the crumbled material to said nodulising cup comprises means defining a scraping edge disposed in the path of said compressed material for crumbling the same and means defining a passage for conveying a passage for conveying the crumbled material to said nodulising cup.

13. Apparatus according to claim :12, wherein said passage comprises separating means for selectively conveying crum led material of predetermined size to said nodulising cup.

14. Apparatus according to claim 4, further comprising delivery means associated with said second nodulising cup for supplying further material to said second cup, said second cup adding said further material to the nodules fed thereto from said first cup, said last-named nodules serving as a core for said further material.

15. Apparatus as claimed in claim 12, wherein said support is inclined to the horizontal axis of the apparatus and said scraper is arranged on its upper portion.

16. Apparatus as claimed in claim 12, wherein said feeding means are arranged above the lower side of said inclined support.

17. Apparatus as claimed in claim 1, wherein said support has an annular shape, and wherein said transporting means extend through a central opening thereof toward said nodulising cup.

l8. Apparatus according to claim 12, wherein said support defines a plurality of U-shaped annular grooves and said scraper includes a plurality of mating teeth.

19. Apparatus according to claim 12, wherein said support defines a plurality of V-shaped annular grooves and I said scraper includes a plurality of mating teeth.

20. Apparatus according to claim 12, wherein said scraper defines a plurality of openings for permitting too fine particles of the compressed material to fall therethrough, so that these will continue to be compressed by said moving support and will be continued to be mixed with material from said feeding means.

21. Apparatus according to claim 4, wherein said first nodulising cup has an annular shape and wherein said feed means feed said ball-like nodules from said first nodulising cup through the central opening thereof to said second nodulising cup.

22. Apparatus as claimed in claim 4, wherein said second nodulising cup has an annular shape and wherein said discharge means transport said ball-like nodules from said cup through the central opening thereof.

23. Apparatus as claimed in claim 1, including first conduit means mounted over said support for transporting a liquid to said material for moistening the same.

24. Apparatus as claimed in claim 1, including second conduit means mounted over said nodulising cup for conducting a binding agent to said compressed material to enhance the formation of said ball-like nodules.

25. Apparatus as claimed in claim 4, wherein conduit means is mounted over said second nodulising cup for conducting a binding agent to said ball-like nodules.

26. Apparatus as claimed in claim 4, including at least one vane adjustably mounted immediately adjacent to said second nodulising cup, guides said ball-like nodules of predetermined size to said discharge means and permits said ball-like nodules smaller than said predetermined size to pass between said second npdulising cup and said vane for further rolling.

whereby said vane selectively 27. Apparatus as claimed in claim 3, wherein said References Cited in the file of this patent roller is resiliently mounted in said apparatus, the outer periphery of said roller abutting against said moving UNITED STATES PATENTS support and resiliently compressing material moving 2,293,439 Lloyd Augnl8, 1942 jointly with said support. 5 2,709,833 Wiklund June 7, 1955 28. Apparatus according to claim 4, in which means is 2,789,894 De Vaney Apr. 23, 1957 provided in the rotative path of said second nodulising 2,793,109 Huebler et a1 May 21, 1957 cup, eccentric to the axis of rotation of said second nodulising cup for periodically deflecting the material carried FOREIGN PATENTS by said second nodulising cup. 10 915,072 Germany July 15, 1954 

